Hoya is in the family of the milkweed that is a famous food of the monarch butterfly caterpillars. They belong to the same family Apocynaceae. Hoyas are normally growing wildly in tropical forests of Southeast Asia, Asia, and Papua New Guinea. It got famous only lately from a group of hobbyist collectors from temperate countries. Today they are found mostly in collector gardens of temperate countries like Europe, USA, Canada, and Australia. The Philippines alone has, more or less, 150 hoya species and more waiting to be named. Countries like Thailand, Indonesia, and Borneo also have their shares pursued much by collectors and hobbyists.
I will be presenting here some Philippine Hoya species that you will surely love to have in your own gardens. I just warn you, hoya collection is addictive and it is also contagious. Do not blame me later that I did not warn you!
Flower and Plant Description
Hoyas are normally epiphytes, or plants growing on trunks and branches of trees. There are also a few called lithophytic hoyas that thrive on rocks. Most hoyas are vines and a few species are erect and bushy, and have milky sap just like the milkweed. Moreover, even without the flowers yet, the leaves alone are already aesthetically beautiful. In the wild they get nutrients from decomposing organic debris in their habitat. So, in domestic and garden cultivation they are provided with whatever nutrients and conditions they need to simulate the original habitat they are found in. Successful cold country growers make provisions like rooms with controlled temperatures, humidity, aerators, and artificial lights to grow them. But here in the tropics they are growing in our open gardens with our normal environmental conditions.
Hoya flowers are lumped in circular bunches of small flowers technically called umbels. The petal-like structures are corolla and the star-shaped parts at the center are corona. Nectar normally oozes out from the bottom of those coronas, and some species become very colorful due to the nectar. Every species also has a distinctive scent, from slightly sweet to extremely fragrant, that probably entices special insect pollinators. However, no studies have yet been done on this aspect. Another special characteristic of hoya is its flower opening later in the afternoon until early evening, concomitant with simultaneous scent emission. Its scent is so powerful that you immediately know a hoya is blooming in your garden as soon as it opens.
Present Industry System
Most of the older identified hoya species were directly collected from the wild decades ago by individual private collectors from temperate countries. Nurseries in those countries supply hobbyists in their areas. A system of hoya industry and export market is also thriving well in Thailand. More and more nurseries are being developed, and most of the international hoya collectors go there to get newly collected species. On the other hand, Thai growers come here, to the Philippines, to collect more species from small collectors and growers. Hoya industry here in the country is not yet as good as other country counterparts, and sometimes getting specimen locally is not anymore possible. We realized its importance only just very recently, when existence in the wild is already dwindling or sometimes gone! Our only option is to source them from foreign collectors who have previously collected them. It is just sad that we do not have a developed hoya export market here in the country, where plenty of the species come from.
Andrea B. Agillon, PhD, is a Horticulturist/Plant Physiologist who has almost a hundred hoya species among her other collections of ornamentals like hippeastrum and crinum.